I wonder how well modern JVMs compare to C++ compilers from 1998?

I'd say that statements like that are subject to some degree of interpretation. It's hard for one runtime to be definitively faster than another runtime. It is, however, quite possible for one runtime to have cases where it is better, cases where it is worse, and cases where it is equivalent such that it is reasonable to say that it is "as fast as" the other. Java tends to be a bit slower than C++ still, but the differences between it and "as fast as" are trivial enough that a number of HFT systems, for example, are written in Java.

While I think the comment here leaves that open as a possibility, the second sentence of the article it's from makes it pretty clear. "Specifically, Sun says that a platform-independent Java program delivered as bytecodes in class files will run on Hotspot at speeds on par with an equivalent C++ program compiled to a native executable."

There's not a lot of wiggle room there.

Considering that I can get different performance for the same C++ program simply by using different compiler, or even different compiler options, I'd say that there's a lot of wiggle room.

Actually, there is a country mile of wiggle room there. It doesn't have to be true of all programs for one, and "on par with" gives you plenty of wiggle room.

There's nothing wrong with trying to sell your product. But I hope Sun's salesmanship doesn't continue to deceive people.